scholarly journals Inter-Crystal Molecular Rearrangement/Reactions and Intra-Crystal Reactions Retaining the Memory of Original Crystal Structures

2013 ◽  
Vol 55 (1) ◽  
pp. 69-74
Author(s):  
Reiko KURODA
Keyword(s):  
Crystal Structures ◽  
Molecular Rearrangement ◽  
Rearrangement Reactions ◽  
Original Crystal

Metal Complexes of 2-[1,2,3-thia(and selena)diazol-4-yl]pyridine and an Unusual Silver-induced Selenadiazole Rearrangement

2002 ◽  
Vol 55 (12) ◽  
pp. 783 ◽  
Author(s):  
Chris Richardson ◽  
Peter J. Steel
Keyword(s):  
Metal Complexes ◽  
Silver Nitrate ◽  
Crystal Structures ◽  
Silver Complex ◽  
Molecular Rearrangement ◽  
X Ray ◽  
Positional Disorder ◽  
Interaction Treatment

Complexes of 2-(1,2,3-thiadiazol-4-yl)pyridine (3) and 2-(1,2,3-selenadiazol-4-yl)pyridine (4) with palladium(II), nickel(II), ruthenium(II), copper(II), and silver(I) reagents are reported. In general, these ligands chelate to the metal but are curiously prone to positional disorder in the X-ray crystal structures of their complexes. With silver tetrafluoroborate, ligand (3) forms an ordered M2L4 complex that contains an unsupported Ag–Ag interaction. Treatment of (4) with excess silver nitrate leads to an intriguing molecular rearrangement that produces a silver complex of 3-formyl-1,2,3-triazolo[1,5-a]pyridine.

Novel Rearrangement Reactions. 1. Molecular Rearrangement via Metathesis between Intramolecular Si−Si and Fe−Fe Bonds

1997 ◽  
Vol 16 (15) ◽  
pp. 3474-3481 ◽  
Author(s):  
Xiuzhong Zhou ◽  
Yongqiang Zhang ◽  
Wenhua Xie ◽  
Shansheng Xu ◽  
Jie Sun
Keyword(s):  
Molecular Rearrangement ◽  
Rearrangement Reactions

Structures and Photochemistry of Inclusion Compounds of 9,10-Dihydro-9,10-ethenoanthracene-11,12-bis(diphenylmethanol)

1997 ◽  
Vol 53 (2) ◽  
pp. 300-305 ◽  
Author(s):  
T. Y. Fu ◽  
J. R. Scheffer ◽  
J. Trotter
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Solid State Reaction ◽  
Inclusion Compounds ◽  
Host Molecule ◽  
Molecular Rearrangement ◽  
Intermolecular Hydrogen Bonds ◽  
Solvent Molecules

Crystal structures have been determined for inclusion complexes of the host molecule 9,10-dihydro-9,10-ethenoanthracene-11,12-bis(diphenylmethanol), with acetone, ethanol and toluene as guest solvent molecules. The host molecule exhibits an intramolecular O--H...O hydrogen bond in each of the complexes, with intermolecular hydrogen bonds to the acetone and ethanol guests. Different photoproducts are obtained from solution and solid-state photolyses; the solid-state reaction involves a relatively small amount of molecular rearrangement, for which a mechanism is proposed.

Molecular rearrangement reactions in the gas phase triggered by electron attachment

2013 ◽  
Vol 15 (13) ◽  
pp. 4754 ◽  
Author(s):  
Benedikt Ómarsson ◽  
Elías H. Bjarnason ◽  
Sean A. Haughey ◽  
Thomas A. Field ◽  
Alexander Abramov ◽  
...  
Keyword(s):  
Gas Phase ◽  
Electron Attachment ◽  
Molecular Rearrangement ◽  
Rearrangement Reactions

Structural contributions of Delta class glutathione transferase active-site residues to catalysis

2010 ◽  
Vol 428 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Jantana Wongsantichon ◽  
Robert C. Robinson ◽  
 Albert J. Ketterman
Keyword(s):  
Crystal Structures ◽  
Glutathione Transferase ◽  
Substrate Binding ◽  
Conformational Stability ◽  
Site Directed Mutagenesis ◽  
Active Site Residues ◽  
Molecular Rearrangement ◽  
Hydrophobic Substrate ◽  
Substrate Processing ◽  
First Time

GST (glutathione transferase) is a dimeric enzyme recognized for biotransformation of xenobiotics and endogenous toxic compounds. In the present study, residues forming the hydrophobic substrate-binding site (H-site) of a Delta class enzyme were investigated in detail for the first time by site-directed mutagenesis and crystallographic studies. Enzyme kinetics reveal that Tyr111 indirectly stabilizes GSH binding, Tyr119 modulates hydrophobic substrate binding and Phe123 indirectly modulates catalysis. Mutations at Tyr111 and Phe123 also showed evidence for positive co-operativity for GSH and 1-chloro-2,4-dinitrobenzene respectively, strongly suggesting a role for these residues in manipulating subunit–subunit communication. In the present paper we report crystal structures of the wild-type enzyme, and two mutants, in complex with S-hexylglutathione. This study has identified an aromatic ‘zipper’ in the H-site contributing a network of aromatic π–π interactions. Several residues of the cluster directly interact with the hydrophobic substrate, whereas others indirectly maintain conformational stability of the dimeric structure through the C-terminal domain (domain II). The Y119E mutant structure shows major main-chain rearrangement of domain II. This reorganization is moderated through the ‘zipper’ that contributes to the H-site remodelling, thus illustrating a role in co-substrate binding modulation. The F123A structure shows molecular rearrangement of the H-site in one subunit, but not the other, explaining weakened hydrophobic substrate binding and kinetic co-operativity effects of Phe123 mutations. The three crystal structures provide comprehensive evidence of the aromatic ‘zipper’ residues having an impact upon protein stability, catalysis and specificity. Consequently, ‘zipper’ residues appear to modulate and co-ordinate substrate processing through permissive flexing.

Pollutant Identification by Selected Area Electron Diffraction

1974 ◽  
Vol 32 ◽  
pp. 532-533
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson ◽  
C. W. Walker
Keyword(s):  
Thermal Treatment ◽  
Electron Diffraction ◽  
Sample Preparation ◽  
Crystal Structures ◽  
Water Samples ◽  
Environmental Samples ◽  
Short Review ◽  
Selected Area Electron Diffraction ◽  
Multiple Component

Selected area electron diffraction (SAD) has been used successfully to determine crystal structures, identify traces of minerals in rocks, and characterize the phases formed during thermal treatment of micron-sized particles. There is an increased interest in the method because it has the potential capability of identifying micron-sized pollutants in air and water samples. This paper is a short review of the theory behind SAD and a discussion of the sample preparation employed for the analysis of multiple component environmental samples.

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